Adobe illustrator cs4- P19

Adobe illustrator cs4- P19

Adobe illustrator cs4- P19: Good designers have many tools at their disposal. Especially in an environment
where most designers have other powerful graphics applications, it
can be diffi cult to choose which one to use for a particular task. For example,
a designer can apply soft drop shadows in Photoshop, Illustrator, and
InDesign—is one application any better than the others for this?

Nội dung Text: Adobe illustrator cs4- P19

514 CHAPTER 15: PREPRESS AND PRINTING
In truth, transparency has always been around—in raster form—in Adobe
Photoshop. The only difference now is that you can apply these effects in
vector form and still edit them late in your workﬂow. At the end of the day,
these transparency effects will become rasterized, leaving you with the same
result as if you had done everything in Photoshop. In any case, let’s take a
closer look at what transparency is and how it works.
Understanding Transparency Flattening
Let’s start with a simple fact: PostScript doesn’t understand transparency. As
you probably know, PostScript is the language that printers and RIPs speak.
Native transparency is understood only by PDF language version 1.4 or
newer (ﬁrst present in Acrobat 5 and Illustrator 9).
NOTE If you’ve used To print objects with transparency, Illustrator must “translate” any transpar-
Photoshop before, ent artwork into a language that PostScript understands. This translation
you may be familiar with the process is called transparency ﬂattening.
term flattening, which com-
bines all layers in a document. The process of ﬂattening is simple, and Illustrator follows two cardinal rules
Although similar in concept, when performing ﬂattening on a ﬁle:
transparency flattening is
different. 1. All transparency in the ﬁle must be removed.
2. In the process of performing rule #1, the appearance of the ﬁle cannot
change.
Both of these rules are followed during the ﬂattening process, with no
exception. Obviously, all transparency has to be removed because PostScript
doesn’t know what transparency is. Additionally, if removing the transpar-
ency would result in your ﬁle changing in appearance, that would mean you
could design something in Illustrator that couldn’t be printed, which doesn’t
make sense either. If you think about it, if you’re removing transparency
from the ﬁle and you’re also keeping the visual appearance of the object,
something has to give, and that something is the editability of your ﬁle.
Let’s take a look at an example of this.
Flattening Artwork
Let’s try an example of ﬂattening:
1. Draw two different-colored circles, one overlapping the other.
2. Set the top circle to Multiply (Figure 15.10).

LEARNING THE TRUTH ABOUT TRANSPARENCY 515
The nice feature of transparency is that you can move the top circle
around or change its color, and any overlapping areas will simply mul-
tiply. The problem is that PostScript doesn’t know what transparency
is and doesn’t know how to print that overlapping area, so transparency
ﬂattening is required.
Figure 15.10 By setting the
top circle to the Multiply
blending mode, you can
see through it to the circle
below, even with Opacity
set to 100%.
3. Select both circles, choose Object > Flatten Transparency, and click OK
(don’t worry about the dialog box, which we’ll get to later).
The ﬁle is now ﬂattened. Does it look any different? It can’t, because of
rule #2, but the ﬁle now no longer contains any transparency and can
be printed on a PostScript device. The difference is that the ﬁle is no
longer editable as it was before it was ﬂattened. Upon selecting the cir-
cles, you’ll ﬁnd that the two transparent circles have now been broken
up into three individual opaque shapes (Figure 15.11).
Figure 15.11 Once the
objects are flattened, the
artwork is split up into
individual opaque pieces,
called atomic regions.
This ﬂattening process happens every time you print something with trans-
parency. However, the ﬂattening happens in the print stream, not to your
actual Illustrator ﬁle. When you choose to print a ﬁle, Illustrator ﬂattens a
copy of your ﬁle and sends the ﬂattened ﬁle to the printer, while leaving
your document intact. It wouldn’t be good if simply printing a ﬁle rendered
it uneditable. In our example, we speciﬁcally ﬂattened the ﬁle using the

516 CHAPTER 15: PREPRESS AND PRINTING
ﬂatten transparency function to see the results, but under normal circum-
stances, you would not ﬂatten the transparency manually—Illustrator would
do that for you automatically at print time.
NOTE Flattening also So, when you print a ﬁle with transparency, this ﬂattening process occurs so
happens whenever that a PostScript printer can print the ﬁle correctly, and this process happens
you save or export your file on the way to the printer, so your Illustrator ﬁle is not affected in any way.
to a format that doesn’t
understand transparency. This example of the two overlapping circles is a simple case of ﬂattening.
For example, EPS (which is However, other examples can display certain side effects. Let’s explore such
PostScript) and PDF 1.3 do a case.
not support transparency.
Flattening with Rasterization
Let’s create another example:
1. As in the previous example, create two overlapping circles.
2. Set the top circle to Multiply.
3. Fill each circle with a linear gradient, but in one of the circles, apply the
gradient on a 45-degree angle.
The result is two circles with gradients, but the area in which these two
shapes overlap appears as two gradients traveling in different directions
(Figure 15.12).
Figure 15.12 This figure
shows two overlapping
circles, each filled with
a gradient on a different
angle.
When this ﬁle is ﬂattened, you know that the result will be three sepa-
rate shapes as in the previous example; however, this example is a bit
different. Although gradients can be preserved in vector form, there’s
no way to describe a crisscross gradient, like you see in the overlapping
area, as a vector. Because of rule #2, Illustrator is not allowed to change

LEARNING THE TRUTH ABOUT TRANSPARENCY 517
the appearance of your ﬁle during ﬂattening, so the only course of action
Illustrator can take is to turn that overlapping area into a raster image.
4. Select both circles, choose Object > Flatten Transparency, and click OK.
You’ll ﬁnd that although the ﬁle looks the same, it now consists of two
vector shapes and a raster image in the middle. Illustrator creates a vec-
tor mask for the middle shape so that the ﬁle will print correctly (raster
images are always rectangular in shape). It’s important to point out that
Illustrator didn’t raster the entire ﬁle; it merely rasterized the portion of
the ﬁle that could not be preserved in vector form (Figure 15.13).
Figure 15.13 Where
appearance can’t be
preserved in vector form,
Illustrator converts parts
of a file into a raster.
At this point, a question should be forming in your mind: If part of the ﬁle
is now a raster image, what is the resolution of that raster? Patience, young
Padawan; we’ll get to that soon. Here’s a review of what you’ve learned to
this point:
• Transparency ﬂattening is required to correctly print a ﬁle with trans-
parency to a PostScript device.
• Transparency ﬂattening happens automatically, in the print stream,
when you print a ﬁle with transparency from Illustrator, InDesign,
Acrobat, or Adobe Reader.
• Transparency ﬂattening may cause certain parts of a vector ﬁle to
become rasterized to prevent a ﬁle from changing in appearance.
Using the Two Levels of Rasterization
In the previous example, where two vector shapes resulted in a portion
of that ﬁle becoming rasterized, Illustrator had no choice but to rasterize

518 CHAPTER 15: PREPRESS AND PRINTING
the middle region because there was simply no other way to preserve the
appearance in vector form. This is one level of rasterization.
However, in some cases a second level of rasterization may occur, even if
the appearance of a ﬁle could be preserved in vector form. Before printing
a ﬁle, Illustrator analyzes the entire document and looks for complex regions
containing many overlapping objects (which would result in a large number
of atomic regions). Illustrator may then choose to rasterize those complex
regions for performance reasons. Although we’ve been trained to think vec-
tor objects are simpler than their bitmapped counterparts, try to imagine an
Illustrator graphic ﬁlled with many overlapping objects with transparency
applied (Figure 15.14). Although it may seem like only several objects at
ﬁrst glance, once those objects are broken up into atomic regions, you may
be looking at thousands of vector shapes, which can take a long time to pro-
cess and print (Figure 15.15). In those cases, Illustrator can save precious
RIP and processing time by rasterizing these complex regions.
Figure 15.14 Using the
Symbol Sprayer tool, you
can easily create a file that
contains many overlapping
shapes. You can also make
some of these symbols
transparent with the
same tool.

LEARNING THE TRUTH ABOUT TRANSPARENCY 519
Figure 15.15 Even though
you may have started with a
small number of objects, the
resulting number of atomic
regions can be extremely
large because of flattening.
As far as the ﬁrst level of rasterization goes, you really have no choice but
to allow Illustrator to rasterize objects where it needs to do so. What you
can do, however, is learn how to build ﬁles that work around this issue (see
“Understanding Object Stacking Order and Transparency Flattening” later
in this chapter). With regard to the second level of rasterization, you can
control how liberal Illustrator is when looking for complex regions. In fact,
you can even disable this second level of rasterization altogether. Finally,
with either level of rasterization, Illustrator always gives you total control
over how these areas are rasterized.
Understanding the Transparency Flattener Settings
As mentioned earlier in this chapter, Illustrator has three transparency ﬂat-
tener presets that you can choose from in the Advanced panel of the Print
dialog box. These settings control how ﬁles with transparency are ﬂattened
at print time. To access these settings, choose Edit > Transparency Flattener
Presets, and click the New button to deﬁne a new preset. Let’s explore
the settings in the Transparency Flattener Preset Options dialog box
(Figure 15.16).

520 CHAPTER 15: PREPRESS AND PRINTING
Figure 15.16 You can
define your own custom
flattener settings, or your
printer or service provider
can define them for you.
• Raster/Vector Balance. This slider is what controls how liberal
Illustrator is when looking for complex regions to rasterize (what we
deﬁned previously as the second level of rasterization). A number closer
to zero (0) gives Illustrator more freedom to rasterize at will, resulting
in faster print times. Moving the slider closer to 100 results in fewer ras-
terized areas but longer print times. At the 100 setting, Illustrator does
not rasterize any parts of the ﬁle for performance reasons, effectively
disabling the second level of rasterization. The High Resolution ﬂat-
tener preset uses this setting. In cases where ﬁles are taking extremely
long to print (or crashing the RIP altogether), adjusting this slider to a
slightly lower setting helps.
• Line Art and Text Resolution. In cases where Illustrator is going to
rasterize line art or text, you can specify a resolution that results in good-
looking, sharp output. You’ll notice that the High Resolution ﬂattener
setting speciﬁes a resolution of 1200 ppi, ensuring that text elements and
vector objects still have nice, clean, sharp edges in ﬁnal output.
NOTE The two resolu- • Gradient and Mesh Resolution. Because gradients and meshes are
tion settings in the continuous tones in nature, they don’t require a resolution as high as
flattener controls are used line art or text. In fact, anything twice your line screen is probably
whenever vector objects are
getting thrown out anyway. Therefore, Illustrator uses this setting to
forced to become rasters
during the flattening process. rasterize elements that can afford to be set at a lower resolution. You’ll
However, live effects, such as notice that the High Resolution ﬂattener preset uses a value of 300 ppi.
Feather and Drop Shadow,
• Convert All Text to Outlines. In cases where text is going to be raster-
use the Document Raster
Effects Resolution setting to ized, chances are that the rasterized text looks a bit chunkier than regular
determine their resolutions. vector text. To compensate for this, you can turn on this option to con-
vert all text to outlines, giving a consistent chunkier look to all of your
text. If you use the method described later in this chapter to move text
onto its own layer, you’ll rarely need to concern yourself with this setting.

LEARNING THE TRUTH ABOUT TRANSPARENCY 521
• Convert All Strokes to Outlines. Similar to the previous setting, this
compensates for disparity between vector and rasterized strokes by con-
verting all strokes to outlines.
• Clip Complex Regions. We mentioned that Illustrator can look for
complex areas of a ﬁle and rasterize them for performance reasons.
However, we know that raster images are always rectangular in shape,
which means it’s possible for “innocent” parts of your ﬁle to become
rasterized simply because they fall into the rectangular bounding box
of the area that is complex. More often than not, this results in stitching,
or noticeable boxes and color shifts. The Clip Complex Regions option
avoids this issue by creating a clipping mask around any rasterized com-
plex region (so the rectangular-shaped raster is masked by the vector
outline of the object). As you can probably understand, this makes for
even more complex ﬁles and can result in longer print times as well.
This option is turned on by default but isn’t applicable in the High
Resolution preset because no complex regions are rasterized at all with
that setting (because it has a Raster/Vector Balance setting of 100).
Understanding Object Stacking Order and
Transparency Flattening
When rasterization occurs during transparency ﬂattening, the last thing you
want to see turning into a raster is text. That’s because you always want text
to be clean and sharp in your printouts. Even at the High Resolution setting,
where text is rasterized at 1200 ppi, that resolution is still less than half of
what most imagesetters set text with—usually upward of 2400 ppi.
Although it’s true that under certain circumstances rasterization must occur
in order to print a ﬁle and maintain its appearance, the way you build your
ﬁles can affect how often this happens. Let’s look at a simple example that
clariﬁes this:
1. Draw a circle, and add a drop shadow to it by choosing Effect >
Stylize > Drop Shadow.
As you learned in Chapter 8, “Working with Typography,” the Drop
Shadow effect is a raster-based effect, and when transparency is ﬂat-
tened, the drop shadow becomes rasterized.

522 CHAPTER 15: PREPRESS AND PRINTING
2. Switch to the Type tool, create some text, and position the text near the
drop shadow (Figure 15.17).
Figure 15.17 Placing text
near an object is common,
especially when you’re add-
ing captions or credit text
near photographs.
3. With the text still selected, choose Object > Arrange > Send to Back.
4. Now select both the circle and the text, choose Object > Flatten
Transparency, and click OK.
Upon close inspection, you’ll see that a portion of the text was raster-
ized. This happened because the text was below the drop shadow in
the stacking order, and to maintain the ﬁle’s appearance when the drop
shadow was rasterized, Illustrator had to include part of the text in the
drop shadow’s bounding area (Figure 15.18).
Figure 15.18 To maintain
the appearance of the file,
Illustrator rasterized the text
that was behind the drop
shadow.

LEARNING THE TRUTH ABOUT TRANSPARENCY 523
5. Choose Edit > Undo to go back to the version before you applied the
Flatten Transparency function, and select the text object.
6. Choose Object > Arrange > Bring to Front.
7. Select the circle and the text, choose Object > Flatten Transparency,
and click OK.
In this case, the text, which was above the drop shadow in the stacking
order, was not affected at all and was not rasterized (Figure 15.19).
Figure 15.19 If the text
appears above the shadow
in the stacking order, the
text is not rasterized
during flattening.
When using transparency features in Illustrator (or InDesign, for that mat-
ter), it’s important to make sure that text always appears above objects with
transparency to avoid unwanted rasterized text issues. Of course, some
designs call for text to appear beneath transparent objects, and in those
cases, you don’t have much of a choice.
Does My File Contain Transparency?
Not every document needs ﬂattening—only those with transparency
in them. The tricky part is that transparency can be introduced into an
Illustrator document in several ways:
• You apply a blending mode or an Opacity value other than 100% in
the Transparency panel.
• You apply the Effect > Stylize > Drop Shadow feature.
• You apply the Effect > Stylize > Feather feature.

524 CHAPTER 15: PREPRESS AND PRINTING
• You apply the Effect > Stylize > Outer Glow feature.
• You apply the Effect > Stylize > Inner Glow feature.
• You apply any “below-the-line” Photoshop effect from the Effect menu.
• You place a PDF ﬁle that contains transparency.
• You place a native Photoshop ﬁle or layered TIFF that contains
transparency.
It would be helpful to know whether the document you’re working on
uses transparency or is even going to require any of the two levels of ras-
terization we spoke of earlier. You can use the Flattener Preview panel
(Window > Flattener Preview) to tell whether a document has transparency
effects in it, as well as to preview areas that will become rasterized in the
ﬂattening process.
By clicking the Refresh button in the panel, Illustrator highlights speciﬁc
areas in your ﬁle in red, indicating where rasterization will occur. You can
enlarge the panel to see a larger image, and you can also click inside the
preview area of the panel to zoom in closer to see more detail. From the
Highlight pop-up menu, you can choose from a variety of items that
Illustrator will preview. If all the items listed in your Highlight pop-up
are dim, that indicates your ﬁle doesn’t have transparency present, and no
ﬂattening is necessary to print your ﬁle (Figure 15.20). For example, when
you choose Transparent Objects, Illustrator shows you where all objects that
use transparency are on your page—although those regions may not neces-
sarily become rasterized. We also mentioned earlier that Illustrator looks for
complex areas of a document; you can see where those areas are by choosing
Rasterized Complex Regions in the pop-up menu (Figure 15.21). Addition-
ally, the All Affected Objects option shows you all the objects that may not
be transparent themselves but that interact with transparency in some way.
(Like with the example we mentioned earlier with the drop shadow and
the text, the text itself doesn’t have transparency applied to it, but if the text
appears below the drop shadow, the text must become rasterized to preserve
the appearance.)
To take advantage of all that the Flattener Preview panel can offer, adjust
the different ﬂattener settings, and preview the results—making changes or
adjustments where necessary—all before you actually print the ﬁle. As an
aside, InDesign and Acrobat Pro also contain a similar Flattener Preview
panel and identical ﬂattener settings (in fact, it’s the same underlying code).

LEARNING THE TRUTH ABOUT TRANSPARENCY 525
Figure 15.20 If your file
contains no transparency,
you don’t have to worry
about the effects of
flattening.
Figure 15.21 You can
use the Flattener Preview
panel to identify areas that
Illustrator deems as complex
regions, giving you a heads
up for what areas will be
rasterized.

526 CHAPTER 15: PREPRESS AND PRINTING
What Kind of RIP Are You Using?
To throw yet another variable into the mix, the kind of printer or RIP you use can also render different results.
For the most part, any Adobe PostScript LanguageLevel 3 device should be able to handle transparency
without issue. Specifically, PostScript version 3015 (which appears in the latest versions of RIPs) has enhanced
functionality to process files that have been flattened. It’s important to remember that flattening has to occur
for any RIP to understand how to print transparency. If your RIP can process PDF files, that doesn’t necessarily
mean it can process PDF files with transparency in them. If you’re in doubt, check with your RIP manufacturer
to find out whether transparency flattening can occur inside the RIP or whether you need to print files from an
Adobe application to flatten them.
Some older print devices are confused by the effects of flattening. For example, a Scitex Brisque RIP (since
acquired by Creo and now Kodak) looks at jobs that are printing and splits up the vector and raster elements
onto two “layers.” The rasterized content prints on a continuous tone (CT) layer at a lower resolution (such as
300 dpi), and line art prints on a separate vector layer at a much higher resolution (such as 2400 dpi). Because
flattening could cause a vector object to be rasterized, the RIP sees that raster only as a CT image and prints it
at the lower resolution. This might cause text that is rasterized to print with noticeably jagged edges. There’s
an update available for Brisque RIPs to address this issue, but that doesn’t automatically mean everyone who
owns a Brisque has installed the update (or knows it exists).
Rampage RIPs also experience similar issues, although turning off the dual-mode setting addresses the problem.
The best advice in any case is to talk with your printer. For any big job, most printers will be happy to run a test
file for you to make sure everything will print correctly. Taking advantage of these opportunities will surely
save you headaches when press deadlines loom. Adobe also has free specialized training materials for print
service providers if your printer needs more information (located online at http://partners.adobe.com/public/
asn/psp/detail.html).
Printing with Conﬁdence
You can avoid accidents by learning to anticipate possible problems. Now
that you’re aware of how transparency works, here are a few ways to ensure
that you get the results you expect when you’re printing from Illustrator:
• Use the right ﬂattener presets—Low Resolution, Medium Resolution,
and High Resolution. For quick proofs to your laser printer, you can
use the Low Resolution or Medium Resolution setting, but when you’re
printing to a high-end proofer or imagesetter, use the High Resolution
setting. You’ll ﬁnd the Transparency Flattener settings in the Advanced
panel of the Print dialog box.

LEARNING THE TRUTH ABOUT TRANSPARENCY 527
• To avoid text becoming rasterized, create a new layer in your Illustrator
ﬁle, and place all your text on that layer. As long as you keep that text
layer as the top layer in your document, you won’t have to worry about
chunky or pixelated text because of rasterization.
• A potential problem is that even if you, as a designer, are aware of trans-
parency, plenty of printers aren’t. If you are sending a ﬁle and aren’t sure
who will be printing it or what they will be using to print it, you might
consider sending the ﬁle as a PDF/X-1a ﬁle. See Chapter 14, “Saving
and Exporting Files,” for more information about PDF/X.
If you’d like an easy way to remember the important steps to get great
results when printing, a small transparency checklist (Figure 15.22,
courtesy of Design Responsibly), is available when you register at
www.peachpit.com/rwillcs4.
Figure 15.22 The transpar-
ency checklist offers a few
quick reminders to help
ensure your file prints
correctly.
Designing with transparency allows you to design creations that were pre-
viously prohibitive and difﬁcult to implement, thus allowing you to save
valuable time while being even more creative. Now that you know how
transparency works and what’s necessary to use it in your workﬂow, give
it a test drive. You’ll be happy you did.

528 CHAPTER 15: PREPRESS AND PRINTING
UNDERSTANDING OVERPRINTS
Hang around a print shop long enough, and you’ll hear the term overprint. In
the world of prepress, overprinting is a way to control how color-separated
plates interact with each other. A printing press imprints each color on a
piece of paper, one after the other, as it runs through the press. Because
of this process, you need to consider certain issues when making color
separations.
For example, say you design some blue text over a yellow background.
When those colors are separated and printed on press, the blue and yel-
low mix, resulting in green text on a yellow background. Therefore, under
normal conditions, when pages are separated, color that appears underneath
other objects is removed so that the color on top is unaffected. In this exam-
ple, the blue text removes, or knocks out, the yellow background underneath
it, allowing the blue to appear correctly when printed.
Overprinting, on the other hand, is a method of overriding a knockout and
forcing overlapping colors to mix on press. In our example, setting the blue
text to overprint means that the yellow background still appears behind it,
and the result on press is green text on a yellow background (Figure 15.23).
Knockout Overprint
Figure 15.23 The text on
the left, by default, knocks
out the background behind
it. The text on the right is
set to overprint, and the
background behind it is
unaffected. Blue Plate Yellow Plate Blue Plate Yellow Plate

UNDERSTANDING OVERPRINTS 529
Why Overprint?
You’d want to apply an overprint when you speciﬁcally want to mix colors
on press. Some designers who work with low-budget jobs that print in two
or three spot colors can simulate other colors by mixing those spot colors.
Before transparency rolled around, designers would also specify overprints
to simulate objects being transparent; you could also simulate shadows or
shading by overprinting with black over other elements.
Overprinting is also essential when you’re creating plates for custom dyes
and varnishes. For example, if you want to create a spot varnish for a par-
ticular photo, you need to create a spot color called Varnish and set it to
overprint, because this allows the photo that appears beneath it to print
(otherwise, the varnish knocks out the photo).
You can easily specify overprinting from the Attributes panel (Window >
Attributes). With an object selected, you can force the ﬁll, the stroke, or both
to overprint. Remember that Illustrator also allows you to specify whether a
stroke is painted in the centerline, inside, or outside a path, and you should
be aware that if you overprint a stroke that’s on the inside or the centerline
of a path, the stroke also overprints the ﬁll of that object.
Trapped in a Corner
Those who work in packaging rely on using overprints all the time for creating
traps—colors that share borders with other colors that overlap slightly. This is
because the materials that are used for many packages and the printing pro-
cesses used (called flexographic printing, or flexo for short) don’t always result
in perfect printing. Remember that the requirements for printing a couple
hundred brochures and printing several million containers of milk can be quite
different. The next time you see a bag of potato chips or a bottle of soda, take
a close look at the label; you’ll be able to see the overprint traps. These are
usually created in Illustrator by setting just the stroke to overprint.

530 CHAPTER 15: PREPRESS AND PRINTING
Handling the Limitations of Overprints
Let’s get technical for a moment. You’ll encounter some limitations when
it comes to using overprints. First, whereas one color plate can overprint
another, an overprint cannot overprint its own plate. For example, if you
have a color that contains cyan and you set it to overprint over a background
that contains cyan, you won’t get an overprint on the cyan plate.
Second, sometimes users specify overprinting for objects colored white.
Usually, white is always a knockout (because it lets the white paper show
through), and setting a white object to overprint would kind of defeat the
purpose. However, these things do happen accidentally. You might have a
logo that you created that’s colored black and that you’ve set to overprint.
Then you might come upon a situation where you need a reverse (white)
version of the logo, so you might just open the ﬁle, color it white, and save
it with a different name, forgetting that you set the ﬁll to overprint. This
would most likely result in the ﬁle not printing properly, because either the
white overprints (making it entirely transparent) or the RIP doesn’t process
the ﬁle correctly.
Previewing Overprints
Because overprints are really PostScript commands that you use when
you’re printing color separations, you’ll always have a problem with display-
ing overprints onscreen or when you’re printing composite proofs to show
a client. In the past, the only real way to proof overprints was by printing
separations and creating a matchprint proof or by investing in expensive
prepress plug-ins. More often than not, a designer would show a proof to
a client and say, “It won’t look like this when it’s actually printed.” If only
there were a better way…
Illustrator offers that better way. By choosing View > Overprint Preview,
you can actually see on your monitor what the effects of overprint com-
mands are. Additionally, in the Output panel of the Print dialog box, the
Simulate Overprint option, when activated, prints composites as they will
look with overprints applied. This is perfect for showing clients exactly what
they are going to get. The Simulate Overprint option is also available in the
Advanced panel of the PDF dialog box, so you can even show your client an
accurate proof via PDF. You disable Simulate Overprint when you choose to
print separations—it’s available only when you’re printing composites.

UNDERSTANDING OVERPRINTS 531
Although overprints are useful (and essential in some workﬂows), our
advice is to talk to your printer before you use them, because some printers
prefer to specify overprints themselves.
Handling Transparency Effects That
Disappear or Print as White Boxes
Has the following scenario ever happened to you?
You create some artwork that contains two spot colors (let’s say Pantone
Blue 072 and Red 032). The logo has a drop shadow behind it, and you’ve
correctly set the Illustrator Drop Shadow effect to use the Blue 072 spot
color, not black. On the Illustrator artboard, the logo appears correctly
against the spot color background (Figure 15.24).
Figure 15.24 In Illustrator,
the Drop Shadow effect
appears correctly against
the spot color background.
Then you save the art as a PDF/X-1a ﬁle because it will be used in an ad
and you want to make sure it will print correctly. Or you save your docu-
ment using Acrobat 4 (PDF 1.3) compatibility. Alternatively, you save your
ﬁle as an EPS ﬁle because maybe you’re required to place this logo into a
QuarkXPress document. The point here to focus on is that you’re saving
your ﬁle to a ﬂattened format.

532 CHAPTER 15: PREPRESS AND PRINTING
The “problem” is that when you open the PDF in Acrobat or Reader, or
when you place the ﬁle into QuarkXPress or InDesign and print the ﬁle to
your laser or ink-jet printer, it comes out looking incorrect—either the drop
shadow disappears completely (Figure 15.25) or a white box appears where
the transparent effect should blend into the background (Figure 15.26).
Figure 15.25 When saving
the file from Illustrator CS4
and viewing or printing the
art outside of Illustrator, the
transparency effect seems
to disappear.
Figure 15.26 When saving
the file from Illustrator CS4
and viewing or printing the
art outside of Illustrator, a
white box appears around
the transparency effect.

UNDERSTANDING OVERPRINTS 533
The key items to focus on here are that you have used a transparent effect
and you’ve used a spot color. Now, you’ll know what’s happening and what
the solution is.
When you have a transparent effect, the result is a mixture of the inks. In NOTE Some RIPs have
this case, the shadow, which is Pantone Blue 072, blends right into the Red built-in settings to
032 background. By default, when one color sits on top of another color, a ignore overprints in files and
instead use their own settings
knockout occurs, as we discussed earlier in this chapter. In other words, the
for overprints. This often
area beneath the top shape is removed from the lower object. Otherwise, results in output that isn’t
the top color will print on top of the bottom color when the paper is run desirable. You can easily fix
through the printing press, causing the two inks to mix. In the case of the these issues by instructing
red and blue colors, the result would be purple in appearance. However, in the RIP to honor the over-
this case, where you want the drop shadow to blend into the background on prints in your files. For exam-
ple, Rampage RIPs have a
press, you have to override that knockout by specifying an overprint.
setting called Preserve
The thing is, Illustrator already knows this, so no action is required on Application Overprint that,
your part. When you print your ﬁle from Illustrator, all these settings are when activated, results in
perfect output.
done automatically, so your ﬁle looks great when you print it—either as a
composite or as separations. The same applies when you save your ﬁle from
Illustrator as a native Illustrator ﬁle and place it into InDesign or when you
create a PDF with Acrobat 5 compatibility (PDF 1.4) or newer.
But when you save your ﬁle to a format that doesn’t support transparency,
Illustrator has to ﬂatten the transparency. And in that process, Illustrator
realizes that in order to preserve the spot colors so that they print in separa-
tions correctly, the drop shadow must be set to overprint the background
color (in Illustrator CS4, the spot color is set to overprint instead).
The problem is that overprint commands are honored only when you print
your ﬁle as separations. When you are previewing your document onscreen
or when you are printing a composite proof of your ﬁle, the overprint com-
mands aren’t used, and either the result will be white where overprinting
should occur or the transparency effect will simply disappear. The ﬁle will
print correctly when you print as separations, because, at that time, the over-
prints are honored (as they should be).